I'm a science, technology and business journalist, currently on staff at irreverent tech news site The Register. I started my career in the Middle East's growing media sector as a reporter on Arabian Computer News, before putting in a couple of hectic years on the business desk of busy daily newspaper 7DAYS in Dubai during the global economic crisis. I returned to tech writing and took on science reporting at The Register, where I've covered everything from the Higgs Boson and dark matter, through space tourism and black holes, to dinosaurs and miracle materials. Follow me on Twitter or Google+

Sunsets Over Saturn's Hazy Moon Teach Scientists About Alien Worlds

Despite the staggering distances between us and the nearest exoplanets, scientists have learned to read the reflected light of their suns to help figure out as much about them as they can, including temperature, composition and structure of their atmospheres. But what about when that light is shining through cloudy atmospheres?

Researchers hit upon using the data we already have from NASA’s Cassini mission about the smog-enshrouded moon TitanTitan to figure out how hazy skies can affect the information we get back about alien worlds light-years away.

To gather data on exoplanets, scientists use the moment that a planet passes in front of its host star as seen from Earth, when the star’s light is filtered through the atmosphere and changed in subtle ways that can tell us a lot about what that world is like.

The light from sunsets, stars and the planets can be separated into component colours to create a spectra that contains hidden details about what it might be like on the surface. But many worlds in our own Solar System are blanketed in clouds and high-altitude hazes – making it likely that exoplanets are too. And if an exoplanet is covered in a haze of clouds, the spectra can be affected.

Clouds and hazes create a variety of complicated effects that scientists have to try to separate out from the information that the spectra is revealing about the signature of the alien atmosphere. Up until now, models used to understand planets outside our Solar System have tended to simplify these effects to avoid the complexity and computing power they would need to factor it all in.

In an effort to improve these models, Tyler Robinson, a postdoctoral research fellow at NASA’s Ames Research Centre, and his colleagues used observations called solar occultations taken by Cassini of Titan’s sunsets to treat the moon as a transiting exoplanet.

“Previously, it was unclear exactly how hazes were affecting observations of transiting exoplanets,” said Robinson. “So we turned to Titan, a hazy world in our own solar system that has been extensively studied by Cassini.”

The team used four observations of Titan made between 2006 and 2011 using Cassini’s visual and infrared mapping spectrometer instrument, which showed that high hazes could strictly limit what the spectra can reveal about distant worlds.

If an exoplanet is particularly hazy, transit observations may only show researchers details about a planet’s upper atmosphere. For Titan, that means around 90 to 190 miles above the surface and high over the bulk of its dense and complex atmosphere.

Titan’s hazes also affect shorter wavelengths – the bluer colours – more strongly, although studies of exoplanet spectra have usually assumed that hazes would affect all colours in similar ways.

Scientists will be able to use the team’s technique on observations of other worlds as well, meaning they should be able to study the atmospheres of planets like MarsMars and Saturn and compare those results with exoplanet research.

“It’s rewarding to see that Cassini’s study of the solar system is helping us to better understand other solar systems as well,” said Curt Niebur, Cassini program scientist at NASA Headquarters.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology, manages the mission.

For more on exoplanets and other science and tech news, follow me on Twitter and Google +.

Post Your Comment

Post Your Reply

Forbes writers have the ability to call out member comments they find particularly interesting. Called-out comments are highlighted across the Forbes network. You'll be notified if your comment is called out.